Solid Oxide Cell Performance: Spatially Resolved Oxygen Electrode Stability

Abstract

Several aspects of TNO SOC performance characteristics will be discussed, with a focus on steam electrolysis performance and lifetime behaviour during endurance tests of several thousand hours. Excellent steam electrolysis performance of the TNO SOE cells is observed at thermoneutral voltage, achieving current density values of −1.7 A/cm2 at an operating temperature of 750 °C. Lifetime assessment and material degradation of the SOC will be discussed, with a focus on the analysis of observed degradation phenomena in the oxygen electrode material. As oxygen electrode degradation can be critical for SOC performance in a stack environment, it is important to have a good understanding of the degradation processes and the ability to monitor them. At TNO, a novel approach of high-resolution 2D mapping of the lateral conductivity of the oxygen electrode has been used as an effective tool for quality control and validation of the oxygen electrode development. Additionally, the combination of 2D sheet resistance mapping, SEM-EDX and XRD techniques provides a powerful combination of tools to obtain a spatially resolved (3D) view of the localized degradation observed in the oxygen electrode after several thousand hours of steam electrolysis.